Oilpan: Replace most of RefPtrs for Event objects with oilpan's transition types

Source/core/events/Event.cpp

 /*
  * Copyright (C) 2001 Peter Kelly (pmk@post.com)
  * Copyright (C) 2001 Tobias Anton (anton@stud.fbi.fh-darmstadt.de)
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2003, 2005, 2006, 2008 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 162 matching lines @@
 
     m_target = target;
     if (m_target)
         receivedTarget();
 }
 
 void Event::receivedTarget()
 {
 }
 
-void Event::setUnderlyingEvent(PassRefPtr<Event> ue)
+void Event::setUnderlyingEvent(PassRefPtrWillBeRawPtr<Event> ue)
 {
     // Prohibit creation of a cycle -- just do nothing in that case.
     for (Event* e = ue.get(); e; e = e->underlyingEvent())
         if (e == this)
             return;
     m_underlyingEvent = ue;
 }
 
 EventPath& Event::ensureEventPath()
 {
@@ skipping 12 matching lines @@
         return StaticNodeList::createEmpty();
     size_t eventPathSize = m_eventPath->size();
     for (size_t i = 0; i < eventPathSize; ++i) {
         if (node == (*m_eventPath)[i].node()) {
             return (*m_eventPath)[i].treeScopeEventContext()->ensureEventPath(*m_eventPath);
         }
     }
     return StaticNodeList::createEmpty();
 }
 
-void Event::trace(Visitor*)
+void Event::trace(Visitor* visitor)
 {
+    visitor->trace(m_underlyingEvent);
 }
 
 } // namespace WebCore